Comparative cellular localization of corticotropin and melanotropin in lerot adenohypophysis (Eliomys quercinus). An immunohistochemical study.

Corticotropin and melanotropin producing cells were localized in the adenohypophysis of normal Lerots by using antibodies against synthetic corticotropins (anti beta1-24 ACTH, anti alpha17-39 ACTH, anti alpha25-39 ACTH), and melanotropins (anti alpha MSH, anti beta MSH). All the anticorticotropin sera stained the same cells both in the anterior lobe and in the intermediate lobe. The anti alpha MSH serum only stained a few cells, exclusively located in the intermediate lobe. These alpha MSH cells were not stained with anticorticotropin antibodies. The anti beta MSH serum revealed all the cells stained with anticorticotropin and anti alpha MSH sera. Absorption tests showed that the 4-10 heptapeptide common to ACTH and MSH, is not responsible for the immunohistochemical staining. The staining of only some corticotrophs with the anti 4-10 ACTH serum might indicate the presence in these cells of a peptide with an accessible 4-10 site. These results are discussed.